Re: [Qemu-devel] KVM: Windows 64-bit troubles with user space irqchip

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On 02/02/2011 04:52 PM, Jan Kiszka wrote:
On 2011-02-02 15:43, Jan Kiszka wrote:
>  On 2011-02-02 15:35, Avi Kivity wrote:
>>  On 02/02/2011 04:30 PM, Jan Kiszka wrote:
>>>  On 2011-02-02 14:05, Avi Kivity wrote:
>>>>   On 02/02/2011 02:50 PM, Jan Kiszka wrote:
>>>>>>>
>>>>>>    Opps, -smp 1. With -smp 2 it boot almost completely and then hangs.
>>>>>
>>>>>   Ah, good (or not good). With Windows 2003 Server, I actually get a Blue
>>>>>   Screen (Stop 0x000000b8).
>>>>
>>>>   Userspace APIC is broken since it may run with an outdated cr8, does
>>>>   reverting 27a4f7976d5 help?
>>>
>>>  Can you elaborate on what is broken? The way hw/apic.c maintains the
>>>  tpr? Would it make sense to compare this against the in-kernel model? Or
>>>  do you mean something else?
>>
>>  The problem, IIRC, was that we look up the TPR but it may already have
>>  been changed by the running vcpu.  Not 100% sure.
>>
>>  If that is indeed the problem then the fix would be to process the APIC
>>  in vcpu context (which is what the kernel does - we set a bit in the IRR
>>  and all further processing is synchronous).
>
>  You mean: user space changes the tpr value while the vcpu is in KVM_RUN,
>  then we return from the kernel and overwrite the tpr in the apic with
>  the vcpu's view, right?

Hmm, probably rather that there is a discrepancy between tpr and irr.
The latter is changed asynchronously /wrt to the vcpu, the former /wrt
the user space device model.

And yet, both are synchronized via qemu_mutex. So we're still missing something in this picture.

Run apic_set_irq on the vcpu?

static void apic_set_irq(APICState *s, int vector_num, int trigger_mode)
{
    apic_irq_delivered += !get_bit(s->irr, vector_num);

    trace_apic_set_irq(apic_irq_delivered);

    set_bit(s->irr, vector_num);

This is even more async with kernel irqchip

    if (trigger_mode)
        set_bit(s->tmr, vector_num);
    else
        reset_bit(s->tmr, vector_num);

This is protected by qemu_mutex

    apic_update_irq(s);

This will be run the next time the vcpu exits, via apic_get_interrupt().

}

Did you check whether reverting that commit helps?

--
error compiling committee.c: too many arguments to function

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